<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>CSS的三种位置</title>
    <link rel="stylesheet" href="Demo.css" >
    <style>

        p{
            color: blue;
        }
        h4{
            color: green;
            background-color: yellow;
        }
    </style>
</head>
<body>
    <div>我是div</div>
    <div>我是div</div>
    <div>我是div</div>
    <hr>
    <!-- Css行内样式-->
    <h4 style="color: red">我是标题</h4>
    <h4>我是标题</h4>
    <h4>我是标题</h4>
    <hr>
    <p>我是段落</p>
    <p>我是段落</p>
    <p>我是段落</p>
</body>
</html>